There is provided an improved process for extracting hydrocarbons and the like from a hydrocarbon-bearing ore and more particularly an improved process for extracting hydrocarbons from hydrocarbon-bearing ores such as diatomaceous earths and the like by forming the ore into pellets.
Many earth formations contain deposits having substantial amounts of hydrocarbons. Oil-bearing diatomaceous earths, tar sands and other deposits contain varying degrees of hydrocarbons. A variety of extraction processes for removal of oil from such ores have been proposed. These may be divided into several categories including pyrolysis or coking, aqueous extraction and solvent extraction. A number of these processes are described in U.S. patent application Ser. No. 450,265 entitled "Extraction Process and Apparatus for Hydrocarbon-Containing Ores."
As noted in Perry's Chemical Engineers Handbook (4th Edition, 1969) page 8-59 et. seq. (hereinafter Perry's) the building up of solid masses of particles from small particulates has long been used as a means of creating definite and useful shapes. As indicated in Perry's there are numerous reasons for doing this, including the need to reduce dust, to prepare a material so that it will not cake or lump, to densify the material for more convenient storage, to create uniform blends which can be handled without segregation and to prepare the material for further processing such as in briquetting or tableting where high apparent density and freedom from dusting are important. Size enlargement has been used in the sintering, nodulizing or briquetting of some types of ores and the nodulizing, extrusion and pelleting of feeds.
When reduced in size, many hydrocarbon-bearing ores become largely impermeable to liquids. This in turn limits the extent to which an extracting medium can be brought into contact with the hydrocarbon-bearing ore. Various attempts have been made to solve this problem, including by use of continuous stagewise, countercurrent extraction-decantation as described in U.S. Pat. Nos. 4,239,617 and 4,167,470.
Forming the ore into pellets did not initially appear workable, particularly since it was believed that any additive used to form pellets would hinder or prevent extraction and decrease the surface area of the ore exposed to an extracting medium. It was also felt that even if workable to some degree, pellet formation would add process steps and increase energy and equipment costs sufficiently to make its use counter-productive. However, it has been discovered that hydrocarbon-bearing ores such as diatomaceous earth and the like may be advantageously extracted by forming the ore into pellets in the manner claimed herein.
Prior processes also suffer from one or more of several defects or limitations. Thus, prior processes may fail to adequately mate process yields with process energy or materials requirements. For example, some processes using extracting solvents fail to recover a sufficient amount of extracting solvent for reuse in the extracting process. Other processes fail to efficiently recover the extracting solvent. There are also problems associated with the presence of fines including fines removal from product streams. Still other processes produce emulsions, which are difficult and relatively expensive to handle. Yet other processes produce waste products which are likewise difficult to handle, while other processes use equipment which must be specially fabricated for use in the particular process. These and other defects or limitations are minimized if not eliminated by the present inventive method.